A chemical transport process for the growth of zinc sulfide single crystals is described. The reaction employed isZnCl2(g)+H2S(g)=2HCl(g)+ZnS(s).The rate of transport of ZnS is discussed, and details of the thermodynamics of the system and the conditions for the growth of single crystals with a pure cubic structure are given. Crystals having this structure and as high a chemical purity have been difficult to obtain heretofore. The chemical analysis and some of the luminescent properties of these crystals are described briefly.